White 1 is tesuji and black 2 is best. White connects underneath and
black jumps ahead of him with 4, calmly pressing white along the second
line. After black 12, white is alive with one eye in the corner and one
eye on the edge, but black can play one point below 12 and force an
answer and his influence towards the centre is superb.

Dia 2 shows whites correct play. Black 6 forces white 7 or white
will die unconditionally. The result is ko, because of course black 8
will take white 3.

The point of the ko is this: if White wins the ko, he will live in
the corner, but even if he loses the ko he will get two successive moves
elsewhere.

Of course, Black gets two successive moves elsewhere if White wins,
but the decision to invade the corner in the first place was Whites, so
you can assume that White has taken this into account.

Note that if Black wins the ko, he will have played five moves in the
corner to Whites four. So isnt the result just the same as Black
playing one move to defend the corner? Yes it is, except that, again, it
was Whites decision to start the ko. So the question boils down to
this; if White has made a threatening move elsewhere instead of white 1,
would Black have ignored it and made a protecting move, say at 3?

When Black has made a one point jump from hoshi, the commonest
amateur sequence is that in Dia 3. White 11 could be played one point
to the right. White is easily alive, in fact too easily; by
naively pushing at 3 he has made Black unnecessarily strong on the
outside. Black has no weaknesses to speak of and can now play elsewhere.

A more cunning move is white 3 in Dia 4. After white 7, white can
either capture 4, or jump to A. Positions like this in which black still
has some weaknesses are vastly preferable to the settled uninteresting
sequence of Dia 3.

Black 4 is given in the diagram because it is the commonest and
simplest move, but it is not the professional move, which is to jump to
A instead. White then lives in the corner, getting a group which is very
similar to that achieved by capturing 4 in this diagram. But there is a
subtle possibility left that if black gets a move somewhere above
A he can spring on white a sequence that kills him. Black should
also think of leaving white with weaknesses!

This sequence may be found in standard joseki books. Desperate pleas
from readers for enlightenment may be heeded in the next issue!

This article is from the
British Go Journal
Issue 41
which is one of a series of back issues now available on the web.